Abstract

Probes based on electro-optic and magneto-optic effects can provide a complete characterization of electromagnetic behavior. Time-domain magneto-optic sampling has been investigated by Freeman et al. to examine spin relaxation and magnetic resonance effects, by Elazzabi et al. to measure picosecond current pulses, and by Riordan et al. to sample transient THz beams^1-3. In the frequency domain, Wakana et al. have examined low-frequency RF circuits using a magneto-optic probe with a CW laser.⁴ The signal-to-noise ratio obtained from magneto-optic probes is typically far less than that obtained from electro-optic probes of similar physical dimensions. In this paper, a frequency-domain technique for sensitivity enhancement is presented. By tuning the probe dimensions to form a resonant cavity at the frequency of interest, the magnetic-field inside of the probe becomes a magnified representation of the sampled field, thereby improving the resulting signal-to-noise ratio. A short pulse laser is utilized to achieve millimeter-wave operation, thus providing the means to perform internal node diagnostics on high-frequency circuits and radiating structures.

© 2002 Optical Society of America